Ink-jet printers of the type disclosed and claimed in U.S. Pat. No. 4,872,026, issued Oct. 3, 1989, and assigned to the same assignee as the present application, commonly include a service station for storing the pen(s) during non-use and for performing other operations, such as priming or clearing the nozzles of the pen, sealing the printhead during non-printing operations, and cleaning the printhead.
Dealing with any ink removed from the pen by priming can be messy. The solution posed in the above-mentioned U.S. Pat. No. 4,872,026 utilized both a spittoon and a cap chamber. All nozzles in the printhead are cleared periodically by firing into the spittoon during printing, and all nozzles are fired into the cap chamber each time the cap is engaged to cover the printhead portion of the pen during non-printing operations. Firing into the cap chamber provides a reservoir of ink that acts as a moisture source to keep the printhead from drying up during printing. Attached to the bottom of the cap chamber is a peristaltic pump, which comprises a plastic tube, a roller, and a pump body. One end of the tube is attached to the bottom of the cap chamber, while the other end terminates in free space, over an absorber pad. The absorber pad is used as a holding vessel while any ink that reaches the absorber pad evaporates into the air. The peristaltic pump serves to prime the pen.
The ink-jet engine employed in ink-jet printers, such as that described above, has been successfully utilized in plain paper facsimile machines. Such facsimile machines are being introduced into the market, and incorporate many of the features disclosed in the above-identified U.S. Pat. No. 4,872,026 and other patents related to ink-jet printers.
During normal operation of a thermal ink-jet pen, spitting is required to clear the nozzles of partially evaporated ink before printing. The spittoon is a reservoir that contains this wasted ink. The volatile portion, for example, the vehicle, of the ink in the spittoon will then evaporate over time. In order to speed up evaporation, an absorbent material is placed in the spittoon to spread out the ink and to increase its exposed surface area. However, in high temperature and low humidity environments, a stalagmite of dried ink tends to form, due to the ink chemistry. The stalagmite can interfere with service station operations, and must be eliminated.
Accordingly, means capable of absorbing quantities of ink in the service station of ink-jet facsimile machines while minimizing the formation of stalagmites of ink is required.